1. Field of Invention
Various exemplary embodiments of the present invention relate to a semiconductor device and an operating method thereof, and more particularly, to a refresh operation of a semiconductor device.
2. Description of Related Art
Semiconductor devices often have a plurality of memory cells for storing data. Data retention performance of the memory cells determined by their charge retention characteristic. The reliability of semiconductor device memory cells' is proportional to their characteristics.
Data stored in memory cells substantially deteriorates over time due to leakage and the like.
In order to retain the data stored in memory semiconductor devices perform a refresh operation by reprogramming the same data into memory cells at predetermined periods.
Generally, during a refresh operation a semiconductor device reads data from the memory cells and reprograms the read data back into the memory cells, thereby improving threshold voltage distribution of the memory cells and retaining the data.
However, as the refresh operation is repeated, the memory cells continuously receive the same level of stress, so that electrical characteristics may deteriorate.